Effects Of Serial/Parallel Presentation Of Visual And Aural Input On L2 Incidental Lexical Chunk Acquisition And Discourse Comprehension

Visual input and aural input play an important role in second language learning. Besides research on the comparison between visual and aural input, there are studies which find that the parallel presentation of visual and aural input enables learners to receive information from different channels, hence boosting the second language learning. However, some other studies show that concurrently processing the same information from two modalities can increase learners’ cognitive load, thus impeding the learning results. Moreover, no research on the two kinds of serial presentation of visual and aural input is available. In addition, the main issues that concern researchers in the area of input modality are the vocabulary learning and language comprehension, but no empirical research has examined the effect of input modalities on the acquisition of lexical chunk. In order to figure out the optimized way of combining visual and aural input, the present study, based on information processing model of bi-modal input, is designed to explore the effect of three input modes(reading-while-listening, reading-before-listening, and listening-before-reading) on the second language(L2) incidental acquisition of lexical chunk and discourse comprehension. Besides, how the effect varies among learners with different language proficiency is also considered. Therefore, four research questions are raised as follows:1) What are the effects of serial/ parallel presentation of visual and aural input on L2 incidental acquisition of lexical chunk?2) What are the effects of serial/ parallel presentation of visual and aural input on L2 discourse comprehension?3) What are the effects of language proficiency on L2 incidental acquisition of lexical chunk under different input modes?4) What are the effects of language proficiency on L2 discourse comprehension under different input modes?To answer these questions, 115 English-majored students, including 67 freshmen in three parallel classes and 48 juniors in three parallel classes, were invited to participate in the experiment. Students from one class of freshmen and one class of juniors constituted one of the three experimental groups, which received three types of presentation of visual and aural input, respectively: simultaneous visual and aural input(V+A), visual-before-aural input(VBA), and aural-before-visual input(ABV). According to a language proficiency pretest, no significant difference among the three groups has been found, and each of them was divided into the low proficiency group(LP) and the high proficiency group(HP). Ten target lexical chunks were chosen from an article with a total of 270 words. The subjects were instructed to freely recall and write down the passage as much as possible after the treatments, and then a surprise lexical chunk test that was made up of four tests measuring two aspects of lexical chunk learning(form and meaning) from two forms of modality(written and aural) was administrated. At last, a questionnaire and an in-depth interview were conducted to explore participants’ attention and cognitive process during each input process. Through the data collection and analysis, we found that:1) Generally speaking, the same effect of input modes on the aural translation test and overall lexical chunk learning has been found, with the V+A group performing significantly better than the ABV group. Although the VBA group also gained higher scores than the ABV group did, no significant difference existed. Due to the lopsided development of reading and listening ability, subjects sometimes can understand what they read, but cannot understand what they listen to. The visual assistance in the parallel presentation can help overcome difficulties in listening, while for some learners the listening-before-reading input only provides one chance for processing lexical chunks.2) Different effects of various input modes on discourse comprehension have also been found. Results showed language comprehension under the parallel presentation of visual and aural input was significantly better than that under the serial presentation. Because of the differences between visual and aural input in characteristics, the process and strategies of reading and listening comprehension are distinct. Compared to listening comprehension, second language learners are mostly better at reading comprehension. The parallel presentation exposes subjects to the written text twice, which plays a significant role in the discourse understanding.3) Input modalities had an effect on the overall learning of L2 lexical chunks for both low and high proficiency learners in the immediate post-test. For low proficiency learners, the V+A group performed significantly better than did the ABV group, which could be attributed to the visual assistance in the parallel presentation. For learners with high proficiency, the VBA group performed best, which was significantly better than did the ABV group, because the VBA input can help learners build a connection between written information and phonological information, thus gaining a compound memory of lexical chunks. But the V+A group did not guarantee the best learning outcomes. This can be explained by the redundancy effect; that is, cognitive load can be induced in high proficiency learners while processing the same information from two different sources. Besides, within-group comparisons showed that as language proficiency increased, the overall learning of lexical chunks was improved.4) For learners with low proficiency level, the parallel presentation of visual and aural input induced significantly better comprehension than the two kinds of serial presentation did. For learners with high proficiency, the parallel presentation and the VBA input both led to significantly better comprehension than the ABV input did. The reason why the performance of VBA group differs between low and high proficiency learners is that the high proficiency learners process the passage information twice, while deducing the lexical chunks’ meaning distracts the low proficiency learners’ attention from understanding text. In terms of the within-group comparison, analysis of the results consistently showed a superiority of the high proficiency learners over the low proficiency learners under all the three input modes in L2 comprehension.The above findings of this study have some pedagogical implications. First of all, in the L2 lexical chunk teaching, English instructors can use the parallel presentation of visual and aural input to achieve the best learning results. However, the effect of language proficiency must be taken into consideration, and it may be beneficial for English instructors to adopt different input modes according to the learners’ proficiency level. For instance, as for low proficiency learners, the most favorable way of learning lexical chunk was the reading-while-listening input mode; while for the high proficiency learners, the reading-before-listening input mode was the most effective. Besides, since the parallel presentation of visual and aural input turned to be the most efficient input mode for both low and high proficiency learners in discourse comprehension, which was not in correspondence with the lexical chunk learning, teachers should take the teaching purpose into account when choosing input mode.